DTC B12C5: Engine Start/Stop Switch Failure

NOTE:  If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A - Refer to: Body Electrical Troubleshooting - B-CAN System Diagnosis Test Mode A - Initial Communication and DTC Checks (2015-17), or Body Electrical Troubleshooting - B-CAN System Diagnosis Test Mode A - Initial Communication and DTC Checks (2018-19) .

DTC (Power Control Unit)

1. Problem verification

   -1. Clear the DTCs with the HDS.

   - 2. Press the engine start/stop switch at least 20 times, then wait for at least 20 seconds.

   - 3. Check for DTCs with the HDS.

   DTC Description	DTC
   B12C5 Engine start/stop switch failure

   Is DTC B12C5 indicated?

   YES 

   Go to step 2.

   NO 

   Intermittent failure, the system is OK at this time. Check for loose or poor connections.

2. Determine possible failure area (+B SMART line, SSB GND line or other)

   -1. Turn the vehicle to the OFF (LOCK) mode.

   - 2. Disconnect the following connectors.

   Keyless access/TPMS control unit connector B (36P)

   Engine start/stop switch 10P connector

   - 3. Connect terminals A and B with a jumper wire.

   Terminal A	Keyless access/TPMS control unit connector B (36P) No. 25
   Terminal B	Body ground

   - 4. Measure the voltage between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode Engine start/stop switch 10P connector: disconnected
   Test point 1	Engine start/stop switch 10P connector No. 5
   Test point 2	Engine start/stop switch 10P connector No. 2

   Courtesy of HONDA, U.S.A., INC.

   Is there battery voltage?

   YES 

   The +B SMART wire and SSB GND wire is OK. Go to step 3.

   NO 

   Go to step 6. Refer to:  6

3. Shorted wire check (SS1+, SS2- lines)

   -1. Check for continuity between test points 1 and 2 individually.

   Test condition	Vehicle OFF (LOCK) mode Engine start/stop switch 10P connector: disconnected Keyless access/TPMS control unit connector B (36P): disconnected
   Test point 1	Engine start/stop switch 10P connector No. 1
   Test point 2	Body ground

   Test point 1	Engine start/stop switch 10P connector No. 4
   Test point 2	Body ground

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   Repair short to ground in the wire.

   NO 

   The SS1+ and SS2- wires are not shorted. Go to step 4.

4. Open wire check (SS1+, SS2- lines)

   -1. Connect terminals A and B with a jumper wire.

   Terminal A	Keyless access/TPMS control unit connector B (36P) No. 10
   Terminal B	Keyless access/TPMS control unit connector B (36P) No. 11

   - 2. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode Engine start/stop switch 10P connector: disconnected Keyless access/TPMS control unit connector B (36P): disconnected
   Test point 1	Engine start/stop switch 10P connector No. 4
   Test point 2	Engine start/stop switch 10P connector No. 1

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   The SS1+ and SS2- wires are OK. Go to step 5.

   NO 

   Repair an open or high resistance in the wire.

5. Engine start/stop switch check

   -1. Do the engine start/stop switch test.

   Is the engine start/stop switch OK?

   YES 

   Replace the keyless access/TPMS control unit .

   NO 

   Replace the engine start/stop switch .

6. Open wire check (+B SMART line)

   -1. Measure the voltage between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode Engine start/stop switch 10P connector: disconnected
   Test point 1	Engine start/stop switch 10P connector No. 5
   Test point 2	Body ground

   Courtesy of HONDA, U.S.A., INC.

   Is there battery voltage?

   YES 

   Repair an open or high resistance in the SSB GND wire.

   NO 

   Repair an open or high resistance in the +B SMART wire.